He certainly played up to the role, presumably for egotistical reasons, but most of it was sabre rattling bravado.
My dude, this ignores like 40 years of him being the most unhinged leader in North Africa. He's always been a wild card on the global political stage, swinging wildly from befriending revolutionary leftist, and then immediately dumping them for right winged dictators.
The man literally tried to sell surface-to-air missiles to a street gang in Chicago...... No one had to make him seem crazy, he was crazy.
Now that doesn't mean I think the US should have intervened, but I don't think anyone had to really do any work to make him seem like an insane supervillain.